Thread winding control mechanism for sewing machines



1964 w. J, EDWARDS ETAL 3,

THREAD WINDING CONTROL MECHANISM FOR SEWING MACHINES Filed May 14, 1963 3 Sheets-Sheet 1 INVENTORS. WILLIAM J. EDWARDS AND WITNESS BY W YNE C. SOCKWELL Mafia?! W ADTTORNEY Oct. 1964 w. J. EDWARDS ETAL 3,154,035

THREAD WINDING CONTROL MECHANISM FOR SEWING MACHINES- Filed May 14, 1965 Sheets-Sheet 2 24 ll 36 39 3a 23 55 W l 141 32 9s IOOIOZ I 34 35 V g 22 f:" cm I E 5 I, r 30 99 53.

5: Fig. 2 X M Km 52 3 Q 2| 2 I 59 60 inil 1 58 62 57 Fig. 3.

INVENTORS WILLIAM J. EDWARDS '1 J AND WAYNE C. SOCKWELL WITNESS 64 BY I MZ J W 6.14%

ATTORNEY Oct. 27, 1964 w. J. EDWARDS ETAL 3,154,035

THREAD WINDING CONTROL MECHANISM FOR SEWING MACHINES Filed May 14, 1963 I5 Sheets-Sheet 5 2 9 w W w m 3 M Fig. 7.

SPEED (RPM x 10} TORQUE OZ-IN) INVENTORS. WILLIAM J. EDWARDS AND WAYNE C. SOCKWELL WITNESS BY me z W United States Patent f 3,154,035 Tl-EEAD WlNDliNG CONTROL MECHANISM FUR SEWING MACHENES William J. Edwards, Denville, and Wayne C. Soclswell,

Watchnng, Ni, assignors to The Singer Company, a

corporation of New Jersey Filed May 14, 1963, Ser. No. 286,347 3 Claims. (6i. 112184) This invention relates to lock stitch sewing machines having mechanism associated therewith for replenishing thread on the bobbin, and this invention is especially useful and advantageous as embodied in a lock stitch sewing machine provided with means for replenishing thread on a bobbin in place in the loop-taker during such interrelated motion of the needle and loop-taker as is required for the formation of lock stitches. More particularly, this invention relates to mechanisms associated with such sewing machine bobbin winding mechanisms for signalling the fully wound condition of the bobbin and for preventing over-winding of the bobbin.

It is an object of this invention, in a lock stitch sewing machine having means which may be rendered effective for replenishing thread on a bobbin in place in the looptaker during such interrelated motion of the needle and loop-taker as is required for the formation of lock stitches, to provide a novel and effective arrangement for reducing the speed and finally for stalling the sewing machine drive as the bobbin becomes fully wound to signal completion of winding and to prevent overwinding of the bobbin.

With the above and additional objects and advantages in view as will hereinafter appear this invention comprises the devices, combinations and arrangement of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a vertical cross sectional view of a sewing machine having this invention applied thereto,

FIGS. 2, 3 and 4 each represents an enlarged vertical cross-sectional view taken substantially along line Z2 of FIG. 1 of the loop-taker including fragments of the stitch forming instrumentalities which cooperate with the loop-taker, together with an elevational view of a portion of the bobbin thread replenishing lever shifted approximately 90 about the axis of the loop-taker drive shaft more clearly to illustrate the relationship of the parts and in which,

FIG. 2 illustrates the position of the parts at the initiation of bobbin thread replenishment,

FIG. 3 illustrates the position of the parts when the bobbin becomes fully wound, and

FIG. 4 illustrates the position of the parts when the bobbin thread replenishing mechanism has been rendered ineffective by the sewing machine operator and at the initiation of stitch formation,

FIG. 5 is a perspective view of the bobbin thread sensing element,

FIG. 6 represents a top plan view of the loop taker, and

FIG. 7 is a graph indicating th preferred speed-torque characteristics of an electric motor adapted for use with this invention.

The sewing machine illustrated in the drawings, including the stitch forming instrumentalities and the provisions therein whereby a bobbin thread may be replenished on a bobbin in place in the loop-taker during such interrelated movements of the needle and loop-taker as are required for the formation of lock stitches are similar to that disclosed in the United States Patent of S. J. Ketterer, No. 3,115,855, December 31, 1963. The control mechanism for initiating bobbin thread replenishment, determining selectively the amount of thread to be replenished on the bobbin, and terminating the operation of the bobbin thread replenishing operation is similar to that dis- 3,35%,fl35 Patented Unit. 27., 1964 closed in the copending United States patent application of W. I. Edwards, Serial No. 280,388, filed May 14, 1963.

The following general description of the stitch forming instrumentalities and of the mechanism for controlling the replenishment of bobbin thread will be sufficient to those skilled in the sewing art for an understanding of the detailed description of this invention contained hereinbelow.

The sewing machine frame comprises a bed 11, a standard 12 rising from the bed, and a bracket arm 13 extending over the bed. A main shaft 14 journaled in the bracket arm is operatively connected to impart endwise reciprocatory movement to a thread carrying needle 15. The main shaft 14 is also operatively connected by means of a standard shaft 16, a bed shaft 17, a loop-taker shaft 18 and meshing gears 19, 2d, and 21, therebetween, to impart rotary motion to a loop-taker 22 secured on the looptaker shaft in timed relation with the needle reciprocation and preferably at the rate of twoloop-taker revolutions for each needle reciprocation.

The needle passes endwise through a needle aperture 23 in a throat plate 24 carried on the sewing machine bed. The throat plate is also slotted as at 25 to accommodate a work feeding dog 26 which is preferably driven in a conventional fashion from the actuating mechanism for the needle and loop-taker, that is, from the main shaft 14 or the standard or bed shafts connected thereto, so as to cooperate with the needle and loop-taker in forming lock stitches in a work fabric W constrained on the throat plate by a presser foot 27 spring biased downwardly from the bracket arm.

The loop-taker 22 includes a cup-shaped body portion 343 formed with a loop seizing beak 31, in which body portion is journaled a bobbin case 32 which is restrained against rotation by rotation restraining members 33 and 33' carried by the bed. A bobbin 34 is ordinarily free to turn in the bobbin case, being supported therein by a top flange 35 of the bobbin which rests on the bobbin case and is centered thereon by a spring biased arm 36 pivoted on a pin 3'7 in the bobbin case. The arm 36 is formed with a depending spherical protuberance 38 accommodated in a spherical seat 39 formed in the top flange 35 of the bobbin. The bobbin 34 also includes a bottom flange id somewhat smaller in diameter than the top flange 35. T he arm 36, in bearing downwardly on the bobbin, thus provides a frictional force between the bobbin and the bobbin case resisting turning of the bobbin and providing a tension on the bobbin thread during sewing operation.

The stitch forming mechanism above described may be operated so as to introduce to the bobbin a loop of the thread carried by the needle and to Wind the thread on the bobbin to replenish the under or locking thread supply during continued interrelated movement of the needle and loop-taker as is required for the formation of lock stitches. Instrumental in bobbin thread replenishment is a bobbin winding member 5% carried within the looptaker body portion beneath the bobbin on a rod 51 slidable in an axial bore 52 in the loop-taker shaft 18. The bobbin winding member includes a pin 53 engageable in an arcuate slot 54 in the undersurface of the bottom flange 4b of the bobbin to drive the bobbin when the bobbin winding member is raised. The bobbin winding member is also provided with an annular rib 55 slightly larger in diameter than the lower flange 4b of the bobbin, which rib embraces the lower bobbin flange when the bobbin winding member is raised. A washer 5'7 fixed rotatably with the rod 51 is formed with a tang 58 interlocked in an aperture 5% in the gear 21 on the loop-taker shaft 18 so as to drive the rod 51 in timed relation with the looptaker.

The stitch forming mechanism thus far described and, in particular, the bobbin winding member 50 cooperating with the stitch forming mechanism as described in greater detail in the above referred to Patent No. 3,115,- 855, serves to deflect the needle thread loop into the bobbin upon initiation of bobbin thread replenishment. In the present invention, as will be described hereinbelow, the rib 55 of the bobbin winding member 50 serves a novel function having to do with preventing overwinding or spilling of thread from the bobbin during replenishment thereof.

The vertical position of the bobbin winding member 50, and thus initiation and completion of bobbin replenishment, is controlled by a thread replenishing lever 60 fulcrumed at 61 in the sewing machine bed. The lever 60 is connected to the rod 51 by means of a stout leaf spring 62 secured to the lever by fastening screws 63 and secured to the rod 51 by means of a nut 64.

A push rod 70 pivoted to the lever 69 and protruding upwardly through the bed It may be used by the machine operator to control the winding of the bobbin. When the push rod 70 is depressed, winding of the bobbin will occur and when the push rod is released the bobbin winding will be terminated and the machine will revert to sewing.

Drivingly connected to the sewing machine main shaft 14, as by a worm 93 and worm wheel 94 drive, is an electric motor 95 disposed in the standard at the juncture with the bed. Operation of the electric motor may be controlled by the operator as by a conventional knee or foot controlled rheostat (not shown). The electric motor 95 is preferably of a type having a substantially drooping speed-torque characteristic as illustrated in the graph of FIG. 7. Typical of an electric motor having such characteristic is a series wound commutator motor. FIG. 7 represents the actual speed torque characteristics of such an electric motor when full line voltage of 115 volts, 6O cycle alternating current is impressed across the motor leads.

The control mechanism for bobbin thread replenishment thus far described is similar to that described in greater detail in the above referenced application Serial No. 280,388 to which reference may be had.

Disposed in a slot 08 formed in the bobbin case 32 and pivoted therein by a pin )9 is an arm 100 of a bobbin thread sensing member 101. The inturned free eX- tremity of the arm 100 is formed with a vertically enlarged, slightly concave thread engaging shoe 102 which is arranged as illustrated in FIGS. 2, 3 and 4 projecting inwardly from the bobbin case and disposed between the flanges 35-40 of the bobbin. Extending from the bottom edge of the thread engaging shoe 102, the thread sensing member is formed with an upwardly and outwardly inclined cam surface 103.

When the bobbin winding member 50 is raised into driving engagement with the bobbin and less than a full complement of thread is wound on the bobbin, as illustrated in FIG. 2, the cam surface 103 of the thread sensing member is disposed inwardly of the rim 55 of the bobbin winding member 50. As thread wound on the bobbin increases inside the shoe 102 and forces the shoe outwardly, however, the cam surface 103 engages the rim 55 as illustrated in FIG. 3. Such engagement of the cam surface 103, which together with the bobbin case is restrained from rotation, and the rim 55 on the bobbin winding member 50 which is being rotated by the sewing machine drive motion 95 develops an increasing torque demand on the motor.

The cam surface 103 engages the rim 55 of the bobbin winding member 50 at an angle as illustrated in FIG. 3 and thus gives rise to a force component tending to depress the bobbin winding member 50 and the rod 51 attached thereto. Should the operator maintain the push rod 70 depressed as the cam surface 103 of the thread engaging shoe 102 engages the rim 55 of the bobbin winding member, the spring 62 will resist the downward urging of the rod 51 by the cam surface 103. Preferably the spring constant of the spring 62 is such as to offer sufficient resisting force to the downward urging of the rod 51 as to give rise to sufficient increase in the torque demand applied to the actuating mechanism as to influence the speed characteristics of the electric motor 95.

As the bobbin approaches a fully wound condition, therefore, the speed of machine operation will drop noticeably thus signalling to the operator that bobbin winding should be terminated.

If the operator fails to notice the signal or otherwise persists in an attempt to further wind the bobbin, the frictional resistance imparted by the cam surface 103 on the rim 55 of the bobbin winding member will increase to the point at which the electric motor will stall, thus preventing overwinding of the bobbin.

When the push rod 70 is released to return the parts of the machine into a condition for sewing, the bobbin winding member will drop into the position illustrated in FIG. 4 and the rim 55 thereof will be lowered out of engagement with the cam surface 103 of the thread engaging shoe 102 thus releasing the sewing machine actuating mechanism from the frictional load imposed for the purpose of stalling the motor at the completion of bobbin winding.

Having thus set forth the nature of this invention what is claimed herein is:

1. A look stitch sewing machine having stitch forming instrumentalities including a needle and a loop taker, a flanged bobbin journaled relatively to said loop taker, actuating means interconnecting said needle and loop taker for interrelated movement as is required for the formation of lock stitches, a drive motor operatively connected to said actuating means, means for replenishing thread on said bobbin in place relatively to said loop taker during said interrelated motion of said needle and loop taker, including a bobbin winding member driven by said actuating means and shiftably supported between said loop taker and said bobbin for movement into and out of driving relation with said bobbin, a thread sensing member extending between said bobbin flanges and shiftable in response to a predetermined quantity of thread wound on said bobbin, and interengaging surfaces [formed on said thread sensing and bobbin winding members shiftable into frictional engagement in response to the sensing of a predetermined quantity of thread wound on said bobbin for stalling said drive motor when said drive motor, said actuating means, and said thread replenishing means are operatively connected.

2. A lock stitch sewing machine having stitch forming instrumentalities including a needle and a loop taker, a bobbin case journaled in said loop taker, actuating means interconnecting said needle and loop taker for interrelated movement as is required for the formation of lock stitches, a drive motor operatively connected to said actuating means, means for replenishing thread on said bobbin in place in said bobbin case relatively to said loop taker during said interrelated motion of said needle and loop taker, said replenishing means including a bobbin winding member disposed between said loop taker and said bobbin, a rod secured to said bobbin winding member, means supporting said rod for endwise shifting movement relatively to said loop taker into and out of a bobbin Winding position, an operating lever for shifting said rod endwise, and spring means yieldingly interconnecting said rod with said operating lever, a thread sensing shoe shiftably supported on said bobbin case and disposed between said bobbin flanges to sense a predetermined quantity of thread wound on said bobbin, cam means on said shoe effective when said predetermined quantity of thread on said bobbin is sensed to urge said bobbin winding member out of said bobbin winding po- 5 sition, said spring means yieldingly interconnecting said rod with said operating lever having a spring constant sufficient to resist said effect of said cam means with sufficient force to stall said drive motor.

3. A look stitch sewing machine having stitch forming instrumentalities including a needle and a loop taker, a bobbin journaled relatively to said loop taker, actuating means interconnecting said needle and loop taker for interrelated movement as is required for the formation of lock stitches, an electric motor having a substantially drooping speed-load characteristic operatively connected to said actuating means, means driven by said actuating means for replenishing thread on said bobbin in place relatively to said loop taker during said interrelated motion of said needle and loop taker, means for sensing a predetermined quantity of thread Wound on said bobbin, and means responsive to operation of said bobbin thread sensing means for increasing the load applied on said actuating mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 923,186 Kanmacher June 1, 1909 1,794,255 Stephenson Feb. 24, 1931 2,255,152 Colegrove Sept. 9, 1941 3,103,189 Ketterer Sept. 10, 1963 

1. A LOCK STITCH SEWING MACHINE HAVING STITCH FORMING INSTRUMENTALITIES INCLUDING A NEEDLE AND A LOOP TAKER, A FLANGED BOBBIN JOURNALED RELATIVELY TO SAID LOOP TAKER, ACTUATING MEANS INTERCONNECTING SAID NEEDLE AND LOOP TAKER FOR INTERRELATED MOVEMENT AS IS REQUIRED FOR THE FORMATION OF LOCK STITCHES, A DRIVE MOTOR OPERATIVELY CONNECTED TO SAID ACTUATING MEANS, MEANS FOR REPLENISHING THREAD ON SAID BOBBIN IN PLACE RELATIVELY TO SAID LOOP TAKER DURING SAID INTERRELATED MOTION OF SAID NEEDLE AND LOOP TAKER, INCLUDING A BOBBIN WINDING MEMBER DRIVEN BY SAID ACTUATING MEANS AND SHIFTABLY SUPPORTED BETWEEN SAID LOOP TAKER AND SAID BOBBIN FOR MOVEMENT INTO AND OUT OF DRIVING RELATION WITH SAID BOBBIN, A THREAD SENSING MEMBER EXTENDING BETWEEN SAID BOBBIN FLANGES AND SHIFTABLE IN RESPONSE TO A PREDETERMINED QUANTITY OF THREAD WOUND ON SAID BOBBIN, AND INTERENGAGING SURFACES FORMED ON SAID THREAD SENSING AND BOBBIN WINDING MEMBERS SHIFTABLE INTO FRICTIONAL ENGAGEMENT IN RESPONSE TO THE SENSING OF A PREDETERMINED QUANTITY OF THREAD WOUND ON SAID BOBBIN FOR STALLING SAID DRIVE MOTOR WHEN SAID DRIVE MOTOR, SAID ACTUATING MEANS, AND SAID THREAD REPLENISHING MEANS ARE OPERATIVELY CONNECTED. 